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Origin radius and the interosseous membrane Insertion thumb, proximal phalanx Artery posterior interosseous artery Nerve posterior interosseous nerve Actions extension of thumb at metacarpophalangeal joint Antagonist Flexor pollicis longus muscle, Flexor pollicis brevis muscle | ||
In human anatomy, the extensor pollicis brevis is a skeletal muscle on the dorsal side of the forearm. It lies on the medial side of, and is closely connected with, the abductor pollicis longus.
Contents
Structure
The extensor pollicis brevis arises from the ulna distal to the abductor pollicis longus, from the interosseous membrane, and from the dorsal surface of the radius.
Its direction is similar to that of the abductor pollicis longus, its tendon passing the same groove on the lateral side of the lower end of the radius, to be inserted into the base of the first phalanx of the thumb.
Variation
Absence; fusion of tendon with that of the extensor pollicis longus.
Function
In a close relationship to the abductor pollicis longus, the extensor pollicis brevis both extends and abducts the thumb at the carpometacarpal and metacarpophalangeal joints.